Method for manufacturing organic light-emitting panel

ABSTRACT

An organic light-emitting panel includes a rear board, a heat spreader and a front board. In this case, the rear board has a first surface and a second surface opposite to the first surface. The heat spreader covers over the first surface and extends to the second surface. The heat spreader, which covers over the first surface of the rear board is formed with plural holes. The front board is set on the first surface and the heat spreader. The invention also discloses a manufacturing method of the panel. The method includes the steps of: fitting a rear board into a heat spreader in such a manner that the heat spreader covers over a first surface of the rear board and extends to a second surface opposite to the first surface of the rear board; and adhering a front board to the first surface of the rear board and the heat spreader.

This application is a Divisional of co-pending application Ser. No.10/321,358, filed on Dec. 18, 2002, and for which priority is claimedunder 35 U.S.C. § 120; and this application claims priority ofApplication No. 091118724 filed in Taiwan, R.O.C. on Aug. 19, 2002 under35 U.S.C. § 119; the entire contents of all are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an organic light-emitting panel and amanufacturing method thereof and, in particular, to an organiclight-emitting panel, in which the heat dissipation paths and area maybe improved, and a manufacturing method thereof.

2. Description of the Related Art

In the conventional methods for packaging organic light-emitting diodes,wire layout is made on a surface of the electroconductive glass. In thismethod, however, pins only can be formed on a periphery of theelectroconductive glass. Thus, the large-scale demands for the organiclight-emitting diodes cannot be satisfied, and the resolution of theorganic light-emitting diodes is further limited. Meanwhile, heatgenerated from the organic light-emitting diodes is almost concentratedon the middle of the device, and the problem of poor heat dissipationpaths is also caused.

Another method for packaging organic light-emitting diodes is called asan array area method, in which solder balls and pins serve as metalconductors. Although the method may solve the problem of large-scaledevices, there are some practical problems to be overcome because theprinted circuit board (i.e., rear board) cannot bear the warpage causedby the high-temperature condition during the high-temperature reflowingprocess.

Because about 90% of electric power inputted to the organiclight-emitting diodes is converted into heat, removing redundant heatfrom the organic light-emitting diodes is a big problem to be solved.The above-mentioned package methods have the following drawbacks. First,the heat dissipation paths and the radiation area of the organiclight-emitting panel are not sufficient, and in particular, when therear board is a plastic substrate with a high thermal resistance, theheat cannot be effectively radiated. Second, because the rear board maywarp, the dimensional stability of the rear board may be influenced.

SUMMARY OF THE INVENTION

An objective of the invention is to provide an organic light-emittingpanel, in which the heat dissipation paths may be increased and theradiation area may be enlarged so as to avoid warpage of the rear boardand facilitate the adhesive dispensing process, and a manufacturingmethod of the panel.

To achieve the above-mentioned objective, the invention provides anorganic light-emitting panel including a rear board, a heat spreader anda front board. The rear board has a first surface and a second surfaceopposite to the first surface. The heat spreader covers over the firstsurface of the rear board and extends to the second surface of the rearboard. The heat spreader, which covers over the first surface of therear board is formed with plural holes. The front board is set on theheat spreader and the first surface of the rear board.

In addition, the invention also provides a manufacturing method of theorganic light-emitting panel. The method includes the steps of: fittinga rear board into a heat spreader in a such manner that the heatspreader covers over a first surface of the rear board and extends to asecond surface opposite to the first surface of the rear board; andadhering a front board to the first surface of the rear board and theheat spreader.

Compared to the prior art, owing to the increased heat dissipation pathsand enlarged radiation area, heat generated from the front board may beeffectively transferred to the rear board and then dissipated. Inaddition, since the rear board is fitted into the heat spreader with thesecond surface of the rear board partially exposed, stresses generatedduring the warpage of the rear board may be absorbed and the dimensionalstability of the rear board may be enhanced. Therefore, the drawbackscaused by the warpage of the rear board may be overcome. Furthermore,since the heat spreader is formed with plural holes, it is possible toprevent the conductive adhesive from overflowing during the adhesivedispensing process, and good smoothness of the conductive adhesive maybe obtained. Further scope of the applicability of the present inventionwill become apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawings,which are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a schematic illustration showing the organic light-emittingpanel according to one embodiment of the invention;

FIG. 2 is a schematic illustration showing a rear board of thisembodiment;

FIG. 3 a is a schematic, cross-sectional view showing a heat spreader ofthis embodiment;

FIG. 3 b is a top view showing the heat spreader of this embodiment;

FIG. 4 is a schematic illustration showing the rear board covered by theheat spreader of this embodiment;

FIG. 5 is a schematic illustration showing a front board of thisembodiment; and

FIG. 6 is a block diagram showing a manufacturing method of an organiclight-emitting panel according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The organic light-emitting panel and the manufacturing method thereof inaccordance with preferred embodiments of the invention will be describedwith reference to the accompanying drawings, wherein the same referencenumbers denote the same elements.

Referring to FIG. 1, an organic light-emitting panel 1 according to oneembodiment of the invention includes a rear board 11, a heat spreader 12and a front board 13. The rear board 11 has a first surface 111 and asecond surface 112 opposite to the first surface 111. The heat spreader12 covers over the first surface 111 of the rear board 11 and extends tothe second surface 112 of the rear board 11. The heat spreader 12, whichcovers over the first surface 111 of the rear board 11 is formed withplural holes 121. The front board 13 is set on the first surface 111covered by the heat spreader 12.

As shown in FIG. 2, the rear board 11 of the embodiment is a printedcircuit board (PCB) having internal circuits 113. The printed circuitboard is typically formed by plating with a layer of copper foil on alaminated board made of a composite material and then etching the copperfoil. The composite material is composed of reinforced fibers and resin.

Please refer to FIG. 3 a, which is a cross-sectional view showing theheat spreader 12, and also to FIG. 3 b, which is a top view showing theheat spreader 12. The heat spreader 12 of this embodiment is made by wayof extrusion followed by a surface isolating treatment to make the heatspreader 12 isolated. The heat spreader 12 functions to increase theheat dissipation paths and enlarge the radiation area of the organiclight-emitting panel so as to effectively transfer heat generated fromthe front board 13 to the rear board 11 and then dissipate the heat.

In this case, the heat spreader 12 is made of a metal of, for example,aluminum or copper. The surface of the heat spreader 12 is formed withan oxide of this metal to avoid the short-circuited condition caused byelectroconductive traces formed between the internal circuits 113 of therear board 11 and the cathode 134 (FIG. 5) of the front board 13.

Referring to FIG. 4, the heat spreader 12 of this embodiment covers overthe first surface 111 of the rear board 11 and extends to the secondsurface 112 of the rear board 11. In this case, the rear board 11 may befitted into the heat spreader 12. The heat spreader 12, which coversover the first surface 111 of the rear board 11 is formed with pluralholes 121. The positions of the holes 121 depend on the relativeposition relationship between the internal circuits 113 of the rearboard 11 and the cathode 134 (FIG. 5) of the front board 13.

Referring to FIG. 5, the front board 13 of this embodiment includes atransparent substrate 131, a transparent anode 132, an organicelectroluminescence layer 133 and a metal cathode 134. The transparentanode 132 and the organic electroluminescence layer 133 are arrangedbetween the transparent substrate 131 and the cathode 134.

In this case, the transparent substrate 131 may be a glass substrate, aplastic substrate or a flexible substrate. The plastic substrate and theflexible substrate may be a polycarbonate (PC) substrate or a polyester(PET) substrate, and the transparent substrate 131 has a thickness ofabout 0.2 to 5 mm.

In addition, the transparent anode 132 of this embodiment is formed onthe transparent substrate 131 by way of sputtering or ion plating. Thetransparent anode 132 may be made of an electroconductive metal oxide,which may be indium tin oxide (ITO) or aluminum zinc oxide (AZO) havinga thickness of 500 angstroms or more.

The organic electroluminescence layer 133 includes a hole injectionlayer, a hole transfer layer, a light-emitting layer, an electrontransfer layer and an electron injection layer. The organicelectroluminescence layer 133 having a thickness of about 500 to 3000angstroms is formed on the transparent anode 132 by way of evaporating,spin coating, ink jet printing or printing. In addition, light raysemitting from the organic electroluminescence layer 133 may be blue,green, red, white, or other monochromatic colors.

Next, the cathode 134 is formed by way of evaporating, electron-beamcoating (E-gun) or sputtering. The cathode 134 has a thickness of about500 to 5000 angstroms and may be made of aluminum, aluminum/lithium,calcium, magnesium-silver alloy or silver.

Since the organic light-emitting diode is very sensitive to moisture,defects such as dark spots may be easily generated after the organiclight-emitting diode contacts the moisture, and the lifetime of theorganic light-emitting panel may also be adversely influenced. In thisembodiment, after forming the cathode 134, an organic desiccant layer135 having a thickness of about 1000 to 6000 nm is plated by a CVD(Chemical Vapor Deposition) method. Then, an inorganic desiccant layer136 having a thickness of about 40 to 450 μm is plated by the CVD orsputtering method so as to isolate the device from moisture. Next, thecathode 134 is defined by way of wet etching.

Please refer again to FIG. 1. The front board 13 is adhered to the firstsurface 111 of the rear board 11 and the heat spreader 12 using aconductive adhesive 14 and an adhesive agent 15. In this case, theconductive adhesive 14 is an epoxy resin (silver paste), theelectroconductive property of which relates to the coating thickness andarea. The adhesive agent 15 is a non-conductive adhesive, the functionof which is similar to that of the underfill. In other words, theadhesive agent 15 is used to solve the problem of the global thermalexpansion mismatch of the organic light-emitting panel. That is, therear board 11 is tightly combined with the front board 13 by theadhesive agent 15, and the stresses therebetween are redistributed overthe whole region.

Referring to FIG. 6, the invention also provides a manufacturing methodof the organic light-emitting panel 1. The method includes the steps of:fitting a rear board 11 into a heat spreader 12 in a such manner thatthe heat spreader 12 covers over a first surface 111 of the rear board11 and extends to a second surface 112 opposite to first surface 111 ofthe rear board 11 (S01); and adhering a front board 13 to the firstsurface 111 of the rear board 11 and the heat spreader 12 (S02).

The elements and functions of the organic light-emitting panel 1 in thisembodiment are the same as those of FIG. 1, and detailed descriptionsthereof are omitted.

In step S01, the rear board 11 is fitted into the heat spreader 12 insuch a manner that holes 121 of the heat spreader 12 are aligned withinternal circuits 113 of the rear board 11, respectively.

In this case, the heat spreader 12 is formed by way of press molding.Then, holes 121 are formed at positions corresponding to the cathode 134of the front board 13 and the internal circuits 113 of the rear board 11using a chemical or mechanical way. Next, a metal film (i.e., blackoxidation) forming method is adopted to form a metal oxide layer havinga thickness of 25 to 100 μm on the surface of the heat spreader 12. Inthis case, the metal oxide layer is used to avoid the short-circuitedcondition caused by the electroconductive traces formed between thecathode 134 of the front board 13 and the internal circuits 113 of therear board 11.

In step S02, the front board 13 is adhered to the first surface 111 ofthe rear board 11 and the heat spreader 12, and the organiclight-emitting panel 1 is thus formed. In this case, a conductiveadhesive 14 and an adhesive agent 15 (non-conductive adhesive) areprinted on the first surface 111 of the rear board 11 and the heatspreader 12. Next, the front board 13 is placed on the conductiveadhesive 14 and the adhesive agent 15.

Because the organic light-emitting panel of the invention includes aheat spreader, the heat dissipation paths of the organic light-emittingpanel may be increased and the radiation area thereof may be enlarged.Compared to the prior art, owing to the increased heat dissipation pathsand enlarged radiation area, heat generated from the front board may beeffectively transferred to the rear board and then dissipated. Inaddition, since the rear board is fitted into the heat spreader with thesecond surface of the rear board partially exposed, stresses generatedduring the warpage of the rear board may be absorbed and the dimensionalstability of the rear board may be enhanced. Therefore, the drawbackscaused by the warpage of the rear board may be overcome. Furthermore,since the heat spreader is formed with plural holes, it is possible toprevent the conductive adhesive from overflowing during the adhesivedispensing process, and good smoothness of the conductive adhesive maybe obtained.

While the invention has been described by way of an example and in termsof a preferred embodiment, it is to be understood that the invention isnot limited to the disclosed embodiment. To the contrary, it is intendedto cover various modifications. Therefore, the scope of the appendedclaims should be accorded the broadest interpretation so as to encompassall such modifications.

1. A manufacturing method of an organic light-emitting panel, comprisingthe steps of: fitting a rear board into a heat spreader in such a mannerthat the heat spreader covers over a first surface of the rear board andextends to a second surface opposite to the first surface of the rearboard; and adhering a front board to the first surface of the rear boardand the heat spreader.
 2. The method according to claim 1, wherein theheat spreader which covers over the first surface of the rear board isformed with plural holes.
 3. The method according to claim 1, whereinthe front board includes a transparent substrate, a transparent anode,an organic electroluminescence layer and a cathode.
 4. The methodaccording to claim 1, wherein the front board is adhered to the heatspreader and the rear board by a conductive adhesive and an adhesiveagent.
 5. The method according to claim 4, wherein the conductiveadhesive is an epoxy resin.
 6. The method according to claim 4, whereinthe adhesive agent is a non-conductive adhesive.
 7. The method accordingto claim 1, wherein the rear board is a printed circuit board.
 8. Themethod according to claim 1, wherein the heat spreader is formed by wayof press molding.
 9. The method according to claim 1, wherein the heatspreader is isolated.
 10. The method according to claim 1, wherein theheat spreader is made of a metal, and a metal oxide is formed on asurface of the heat spreader.